Ultrastructural, biochemical and electrolyte compositional changes will be investigated in hypertrophied vascular smooth muscle, used as a model for determining the effects of hypertension on blood vessels. The recently reported increase in intermediate filaments found in hypertrophied portal vein smooth muscle (Berner, Somlyo and Somlyo, J. Cell Biol, in press, 1981) will be investigated by one-dimensional and two-dimensional gel electrophoresis. These studies are designed to determine whether the increase in these filaments is due to new synthesis or polymerization of pre-existing subunit proteins. The identity of the subunit protein in normal and in hypertrophied vascular smooth muscle will also be investigated. Electron probe analysis will be used to determine the changes in electrolyte content of hypertrophied vascular smooth muscle cells and their organelles, using transverse cryosections of flash-frozen material.